CHIRAL DYNAMICS AND HEAVY-QUARK SYMMETRY IN A SOLVABLE TOY FIELD-THEORETIC MODEL

We study a solvable QCD-like toy theory, a generalization of the Nambu -Jona-Lasinio model, which implements chiral symmetries of light quark s and heavy quark symmetry. The chiral symmetric and chiral broken pha ses can be dynamically tuned. This implies a parity-doubled heavy-ligh t meson system, corresponding to a (0-, 1-) multiplet and a (0+, 1+) h eavy spin multiplet. Consequently the mass difference of the two multi plets is given by a Goldberger-Treiman relation and g(A) is found to b e small. The Isgur-Wise function xi(omega), the decay constant f(B), a nd other observables are studied.